i don't know how to feel about the fact that it took so long for them to have their first concert, then 3 members leave, one goes on hiatus and the remaining four are going to be performing the prior line-ups' songs... it makes me uncomfortable

Well, it's true that Nine Muses will be holding a second solo conert next month BUT this time around, Nine Muses will do it as a temporary quartet because number one, Minha, Erin and Hyuna left the group last year. And number two, of course Sungah is currently taking a breather from group promotions in order to focus on DJing for the time being. So yeah, we will just have to happily look forward to it nonetheless.